Quite original, the mechanics are interesting though it's not really easy to understand how they work, for instance when you die from certain things the doors reset, when you die from other things they don't.
I'm not sure how i was supposed to finish the last level but the way i did it felt almost liek an exploit, was i supposed to trap myself in the portal room, then teleport the checkpoint back so the triangle could enter, kill me, come back, do a trickshot to get the flag on the right side then another tricky move to pick it up and throw it at the top before the triangle hitted me ?
Anyway it is quite polished, some collisions issues with doors trapping you inside of them, otherwise good job !